Many microorganisms have been shown to produce hydroxycarboxylic acids such as 3-hydroxypropionic acid (Andreeken, B., and Steinbuchel, A., Applied and Environmental Microbiology (2010), 76, 4919-4925), 3-hydroxybutyric acid (Aslim, B., Caliskan, F., Beyatli, Y. and Gunduz, U., FEMS Microbiol. Lett (1998), 159, 293-297), 3-hydroxyvaleric acid (Steinbuchel, A., Debzi, E-M., Marchessault, R. H and Timm, A., Applied Microbiology and Biotechnology (1993), 39, 443-449) and their polymers in the form of polyalkanoates (US20120129232). Generally, hydroxycarboxylic acids and their corresponding polyalkanoates are produced in response to nutrient limited growth conditions (Brigham, C. J., Kurosawa, K., Rha, C., and Sinskey, A. J., S3 Microbial and Biochemical Technology (2011)). Production of hydroxycarboxylic acids, in particular, 3-hydroxypropionic acid, is of commercial importance as it is easily converted to acrylic acid and other chemicals. As a result, 3-hydroxypropionic acid (CAS number 503-66-2) is a valuable platform chemical.
The production of 3-hydroxypropionic acid by genetically modified microorganisms has been the focus of a number of patents (US20090325248, US20100021978, W02012/0301935, US2012244588 and US20110125118). These patents describe fermentative processes whereby sources of carbohydrate such as sugars or glycerol are converted to 3HP through known modified pathways. Yields are described in various formats, WO2012/0301935 gives results of 0.97 g of 3HP per gram of added glycerol and US20110125118 describes yields in terms of 0.05 g/g dry cell weight/hour or 0.05 g/liter/hour.
More recently, the conversion of carbon dioxide to 3-hydroxypropionic acid was described in Pyrococcus furiosus (WO2013/067326). This organism has been engineered to use carbon dioxide and hydrogen gas to produce 3HP either by cell free extracts or whole cells of the recombinant strain. However, this organism is genetically modified and requires a growth temperature of 70 to 73° C.
Harvested 3HP is converted to acrylic acid via well-established chemical procedures. 5 However, the major issue with all biological processes is that while the yields of 3HP are at commercially useful levels, the molecule is difficult and costly to extract from the background of other material present in the spent bacterial media. In addition, the cost of starter feed stocks also prohibits the commercialisation of biological 3HP production.
WO2013/011292 describes a microorganism which is capable of producing long chain aliphatic carboxylic acids. This document describes a particular strain referred to as Acetobacter lovaniensis FJ1 having accession number NCIMB 41808 (deposited at NCIMB Ltd. (Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen, AB21 9YA) on 12 January 2011 under the provisions of the Budapest Treaty).